Dr. Roess' research has involved the study of luteinizing hormone/chorionic gonadotropin (LH/CG) receptor organization and how this organization modulates receptor function. Her long-term goal is to better understand the role of LH/CG receptor structure in regulation of fertility and how gonadotropins may modulate LH/CG receptor functional events including G-protein interactions, receptor internalization and cAMP activation. During the award period she will examine whether gonadotropin binding causes size changes in functional LH receptor complexes as well as receptor-receptor aggregation on the membrane using biophysical techniques. These studies will use human embryonic kidney cells expressing LH/CG receptors with various C-terminal truncations that affect cAMP activation and receptor internalization. The effects of deglycosylated hCG and native hCG binding on LH/CG receptor association within the membrane will be evaluated on MA-10 cells where binding of deglycosylated hCG to the LH/CG receptor slows receptor down regulation and internalization. Then the association of non-receptor proteins including G-protein subunits and MHC class I antigen with LH/CG receptors will be explored by a photoproximity labeling technique that permits identification and isolation of proteins physically proximal to a known membrane site.